Update target_include_directories to support build and install interfaces

[Nowaterisenough]

This occurred because the INTERFACE include directories were using absolute source paths that are invalid when the target is exported/installed to other systems.

Solution

• Updated target_include_directories to use CMake generator expressions
• Used $<BUILD_INTERFACE:...> for build-time include paths
• Used $<INSTALL_INTERFACE:...> for install-time include paths
• This ensures the target can be properly exported and used by external projects

Changes

• Modified CMakeLists.txt to use proper generator expressions for include directories
• Ensured compatibility with CMake's export/install mechanisms
• Maintained backward compatibility for local builds

Testing

• Local build completes successfully
• CMake generation passes without errors
• Target can be properly exported

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)